Field
The disclosed concept is generally related to electric drive-trains for ships and, more particularly, to electric drive-trains that can replace mechanical drive-train systems utilizing a main reduction gear (“MRG”).
Background Information
A prior art mechanical drive-train system is shown in FIG. 1. This particular system includes two gas turbines 1, 2, which are mechanically connected to the MRG 3 or mechanical gearbox, which then mechanically drives a main shaft 4 and a propeller 5.
The use of electric drive-trains for marine propulsion has become very widespread, and is widely considered to be the future of naval propulsion. This enables the electrical load and the propulsion load to share a common power source, and thereby optimizes fuel efficiency as well as increases the available electrical power.
Existing marine vessels and other ships have space constraints and fixed hull-forms. Hence, retrofitting a mechanical drive-train with an electric drive-train is subject to multiple physical constraints.
Typically, integrated power systems (IPSs) have been relegated to a relatively larger class of marine vessel or ship. This is in large part due to auxiliary equipment, such as switchgear and cooling systems, required to support the relatively large power of the propulsion load. In relatively small marine vessels, a hybrid solution is often proposed which involves coupling a relatively smaller rated electrical machine to an existing gear box in order to provide some of the benefit of the IPS without adding a full set of equipment.